ABSTRACT
In this study we have compared protein secretion in the wild type of S. Typhimurium and the rfaC mutant. We found out that the rfaC mutant was defective in protein secretion. In addition, the rfaC mutant was defective in its invasion into an IPEC-J2 porcine epithelial cell line and also in motility in semisolid agar. Consistent with this, reduced flagella numbers were observed in the rfaC mutant. In the rfaC mutant, there were no defects in flagellin expression as detected by western blot and immune electron microscopy which demonstrated equal amounts of flagellin in the cytoplasm of both the rfaC mutant and the wild-type S. Typhimurium. However, in the wild-type strain only, the flagellin was assembled to spatially restricted areas on the inner side of cytoplasmic membrane. The oligosaccharide core of LPS is therefore required for the assembly of flagella and T3SS secretion machinery followed by protein secretion.
Subject(s)
Bacterial Secretion Systems , Flagella/metabolism , Flagellin/metabolism , Lipopolysaccharides/chemistry , Salmonella enterica/metabolism , Animals , Cell Line , Cytoplasm/chemistry , Epithelial Cells/microbiology , Flagellin/biosynthesis , Microscopy, Immunoelectron , Mutation , Oligonucleotide Array Sequence Analysis , Salmonella enterica/genetics , Salmonella enterica/ultrastructure , SwineABSTRACT
If any new live Salmonella vaccine is introduced in the future, it is quite probable that detailed characterisation of its attenuation will be required. In this study we therefore compared 34 isogenic mutants of S. Enteritidis in aroA, aroD, galE, ssrA, sseA, phoP, rpoS, ompR, htrA, clpP, lon, rfaL, rfaG, rfaC, hfq, sodCI, hilA, sipA, avrA, sopB, sopA, sopE, sifA, shdA, fliC, fur, relA, spoT, rel-spoT, misL, rmbA, STM4258, STM4259 and spvBC genes for their resistance to stresses likely to be expected in the host and for their virulence and immunogenicity in Balb/C mice. We found that the cold and bile resistances essentially did not correlate with the resistances to other stress factors. Resistance to acid pH, heat, polymyxin and serum correlated with each other and also with the attenuation. When the residual virulence and immunogenicity were both considered, mutants in htrA, ompR, aroA, aroD and lon performed the best in mice. Furthermore, when a detailed comparison of polymyxin and serum sensitive mutants was performed, the serum sensitive mutants were more immunogenic.
Subject(s)
Salmonella Infections, Animal/prevention & control , Salmonella Vaccines/immunology , Salmonella enteritidis/immunology , Animals , Female , Gene Deletion , Genes, Bacterial , Mice , Mice, Inbred BALB C , Polymyxins/immunology , Reproducibility of Results , Salmonella Infections, Animal/immunology , Salmonella enteritidis/genetics , Salmonella enteritidis/pathogenicity , Vaccines, Attenuated/immunology , VirulenceABSTRACT
Retron reverse transcriptases are unusual procaryotic enzymes capable of synthesis of low-molecular-weight DNA by reverse transcription. All of the so-far-described DNA species synthesized by retron reverse transcriptases have been identified as multicopy single-stranded DNA. We have shown that Salmonella enterica serovar Enteritidis is also capable of synthesis of the low-molecular-weight DNA by retron reverse transcriptase. Surprisingly, Salmonella serovar Enteritidis-produced low-molecular-weight DNA was shown to be a double-stranded DNA with single-stranded overhangs (sdsDNA). The sdsDNA was 72 nucleotides (nt) long, of which a 38-nt sequence was formed by double-stranded DNA with 19- and 15-nt single-stranded overhangs, respectively. Three open reading frames (ORFs), encoded by the 4,053-bp plasmid, were essential for the production of sdsDNA. These included an ORF with an unknown function, the retron reverse transcriptase, and an ORF encoding the cold shock protein homologue. This plasmid was also able to confer phage resistance onto the host cell by a mechanism which was independent of sdsDNA synthesis.
Subject(s)
DNA, Bacterial/genetics , Plasmids/genetics , RNA-Directed DNA Polymerase/genetics , Salmonella enterica/genetics , Bacteriophages , DNA, Bacterial/biosynthesis , DNA, Single-Stranded/biosynthesis , DNA, Single-Stranded/genetics , Electrophoresis, Polyacrylamide Gel , Molecular Sequence Data , Molecular Weight , Mutagenesis, Insertional , Nucleic Acid Hybridization , Open Reading Frames , Plasmids/chemistry , Salmonella enterica/enzymology , Salmonella enterica/virologyABSTRACT
The authors present an abridged version of the final report of a State research programme. By introduction of a series of provisions and expedient use of funds available for research it proved possible to reduce the incidence of nosocomial infections in surgical patients from 14% to 12% and in a group with multiple injuries in the surgical intensive care unit from 18% to 10%.
Subject(s)
Anti-Bacterial Agents/therapeutic use , Cross Infection/prevention & control , Intensive Care Units , Multiple Trauma/surgery , Humans , Multiple Trauma/microbiology , PremedicationABSTRACT
During 1985-1988 the authors followed up in a prospective investigation 3240 patients admitted to one of the departments in a Surgical Clinic. In the course of hospitalization 430 (13.3%) patients had at least one infection. Among infections urinary infections predominated which were found in 92% of catheterized patients. As to the aetiology, E. coli was found most frequently. From the whole group 1642 (51%) patients were operated. In the category of clean surgical wounds an early infection was detected in 3.7% of the operated patients; depending on the degree of contamination in the other categories this complication was found in 6.8, 19.5 and 28.0% of the operated patients.
